Log in

View Full Version : On the basis of Le Chatelier's principle,explain why Ag2CO3 dissolves when HNO3 is ad


redrddvl
Feb 28, 2013, 09:48 AM
Chemistry question I am stuck on.

sweety_777n
Apr 4, 2013, 08:16 AM
The reaction is an equilibrium represented by the equation

Ag2CO3(s) + 2 HNO3(aq) <----> 2 AgNO3(aq) + H2O(l) + CO2(g)

In a sealed container, the reaction will proceed when HNO3 is added to Ag2CO3 until equilibrium is reached. We will then have a balanced equilibrium, which is dynamic [still proceeding so rate forward = rare backward] and concentrations of each chemical remain constant. CO2 will be present here at a certain concentration and pressure for example.

However, if you carry out the reaction in a beaker or test tube, it is no longer a closed system and we can apply LeChatelier's Principle. He said 'when a constraint is applied to a system in equilbrium, the system will oppose that constraint' Put in simple everyday language, if you mess around with an equilbria, it will try and do the opposite to counteract your messing around!

So in the test tube, the CO2 starts escaping and the concentration and pressure of CO2 drops. What does the system do?. well by Le chatelier it opposes this and tries to up the concentration and pressure of CO2 by producing more. You've let it escape the system says, so I'll make more. So more Ag2CO3 and HNO3 react. Once again the CO2 escapes the tube and more is produced to counteract this. This continues until one of the reactants is all used up and the reaction has in fact gone from left to right rather than remaining in equilibrium